Electroactive polymers are now frequently used in a number of optical devices such as in polymeric light emitting diodes (“PLEDs”) as disclosed in WO 90/13148, photovoltaic devices as disclosed in WO 96/16449 and photodetectors as disclosed in U.S. Pat. No. 5,523,555. One class of electroluminescent polymers are polyfluorenes as disclosed in, for example, Adv. Mater. 2000 12(23) 1737-1750. These polyfluorenes have the advantages of being soluble in conventional organic solvents and have good film forming properties. Furthermore, fluorene monomers are amenable to Suzuki or Yamamoto polymerisation which enables a high degree of control over the regioregularity of the resultant polymer and the formation of block copolymers wherein different blocks have different functions as disclosed in WO 00/55927.
Each fluorene repeat unit of these polyfluorenes is normally provided with two 9-substituents to modifiy the properties of the polymer. For example, alkyl groups have been used as 9-substituents for the purpose of increasing the solubility of the polymer. Other substituents, such as phenyl, have also been used.
The two 9-substituents are often the same for simplicity of manufacture, however this means that the fluorene repeat unit is symmetric which has been found to be problematic in that polymers comprising symmetrical fluorene repeat units have a tendency to aggregate.
To overcome this problem, efforts have been directed towards production of asymmetric fluorene monomers, i.e. fluorene monomers wherein the two 9-substituents are different, as disclosed in WO 00/22026 and DE 19846767. Processes disclosed in these documents include reaction of fluorenone or biphenyl-2-carboxylic acid ester with two different organometallics.
Biphenyl-2-amides are known—see for example WO 00/03743 and U.S. Pat. No. 6,329,534. However, these disclosures do not teach such carboxamides comprising polymerisable groups, asymmetric substitution or a method of forming monomers therefrom. Tetrahedron Letters 22(39), 3815-3818, 1981, describes a process of reacting N-methoxy amides with organometallic reagents to form ketones. The reaction proceeds via a 5-membered intermediate that is resistant to over-reaction to form an alcohol. This disclosure is not concerned with the formation of asymmetric systems, polycyclic systems or monomers.